The studies outlined in this proposal are designed to examine the idiotypy of the antiinfluenza immune response of mice immunized with different strains of influenza A and B viruses. Using monoclonal antibodies to the hemagglutinins of these viruses we will prepare antiidiotypy antibodies to each. These reagents will permit us to compare idiotype expression in different strains of mice and to examine the ontogeny of the immune response following primary and secondary immunization. These studies will provide information on the evolution of the antiHA repertoire during postnatal life, the generation of antiHA immune response and its genetic basis. In addition, these reagents will be used to determine whether or not in some instance monoclonal antibodies prepared against antigenic variants obtained from nature or selected in the laboratory have shared cross-reactive idiotype. These studies should provide insight into the genetics of the immune response to closely related and serologically non cross reactive antigenic variants. Finally, these reagents will be employed to characterize idiotype determinants on lymphocytes which mediate humoral and cellular anti-HA immune response and to manipulate the function of these cells with anti-Id antibody.